Question: If $x \bigtriangledown y = 3x-y$ and $x \bigtriangleup y = 6x+y$, find $2 \bigtriangledown (2 \bigtriangleup 3)$.
First, find $2 \bigtriangleup 3$ $ 2 \bigtriangleup 3 = (6)(2)+3$ $ \hphantom{2 \bigtriangleup 3} = 15$ Now, find $2 \bigtriangledown 15$ $ 2 \bigtriangledown 15 = (3)(2)-15$ $ \hphantom{2 \bigtriangledown 15} = -9$.